JP4134241B1 - Method for producing concrete product and concrete product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a concrete having a high productivity, a good working environment, no sludge generation, excellent product solidity, a synthetic resin pipe on the inner peripheral surface, and a steel material on the outer peripheral surface. It is an object of the present invention to provide a method for producing a concrete product, which can produce a concrete product having improved integrity between a synthetic resin tube and concrete and steel and concrete.
As a synthetic resin pipe, a synthetic resin pipe having a plurality of axially formed grooves formed on the outer surface along the circumferential direction is used, and the inner surface side of the concrete product is configured without being removed after the concrete is placed. High-fluidity concrete is placed between an inner frame made of a resin pipe and an outer frame made of steel that constitutes the outer surface side of the concrete product without being removed after the concrete is placed. According to a method for producing a concrete product, wherein the concrete is molded while left standing.
[Selection] Figure 2

Description

  The present invention relates to a method for producing a concrete product and a concrete product, and in particular, a method for producing a concrete product such as a concrete tube having a synthetic resin tube provided on the inner peripheral surface for imparting a corrosion prevention function, and a concrete product, The present invention relates to a method for manufacturing a concrete product that does not require conventional centrifugal molding or vibration pressure molding, and a concrete product obtained by the manufacturing method.

  In general, when a concrete product is manufactured, a basic process of placing concrete in a mold is included, but depending on the type of concrete product, various methods are adopted. For example, as a concrete pipe manufacturing method, conventionally, concrete placed in a mold is compacted using a large centrifugal force generated by high-speed rotation (also referred to as centrifugal molding method), or concrete is filled. At this time, a method of compacting by applying strong vibration to the mold (also referred to as a vibration molding method) is known.

  However, in the centrifugal molding method, it takes about one hour for one centrifugal molding, and only three pieces can be produced per hour even when a commonly used triple centrifugal molding apparatus is used. It has the problem of low productivity. Further, there is a problem that the noise generated by the centrifugal molding apparatus is extremely large and the working environment is extremely bad. Furthermore, there is a problem in that a large amount of sludge called Noro, which is a mixture of excess water, fine particles of cement and mud in the aggregate, is generated from the peripheral surface of the tube by centrifugal molding, and the processing of the Noro is expensive. is there.

On the other hand, in the vibration pressure molding method, since it is possible to use a concrete with a low water cement ratio, immediate demolding from the mold is possible, and the productivity is high compared to the centrifugal molding method, There is an advantage that no sludge is generated.
However, the amount of cement paste is reduced so as not to cause deformation, deformation, sagging, etc. after molding, and because it uses solid concrete with a low water-cement ratio, it is insufficiently filled even under strong vibrations. As a result, the surface of the concrete pipe obtained by the vibration pressure forming method has a problem that corners, voids such as bean plates, etc. are likely to occur.

  By the way, a synthetic resin pipe may be provided on the inner peripheral surface of the concrete pipe as described above in order to provide an anticorrosion function, and the outer peripheral surface of the concrete pipe is bent when used as a propulsion pipe. A steel pipe may be provided in order to provide a function of increasing resistance to a load and improving external pressure strength, and the manufacturing method of a concrete pipe having such a configuration requires another manufacturing process. However, as a method of manufacturing a concrete pipe having such a configuration, the centrifugal molding method or the vibration pressure molding method as described above is basically employed, and the above-described problems similarly occur. .

  In addition, there are problems inherent to the synthetic resin pipe provided on the inner peripheral surface. That is, in the case of the centrifugal molding method, after forming the concrete pipe by compacting using centrifugal force as described above, a synthetic resin pipe is attached to the inner surface side of the concrete pipe. Since the synthetic resin pipe is attached as the inner pipe, there is a problem that it takes time.

In addition, when a synthetic resin tube is installed in advance as an inner mold rather than retrofitting and centrifugal molding is performed, there is a risk of mold displacement and distortion due to high-speed rotation. In addition, since the concrete is tightened to the outer mold side by centrifugal molding, there is a high possibility that a gap is generated between the inner mold and the concrete. As a result, the synthetic resin pipe and the concrete cannot be kept together, and there arises a problem that the function of the synthetic resin pipe as the inner pipe cannot be achieved.
On the other hand, as a method of manufacturing a concrete pipe in which a synthetic resin pipe is provided on the inner peripheral surface, and employing a vibration pressure forming method, there is a technique as described in Patent Document 1 below. In this Patent Document 1, a synthetic resin pipe is erected in the longitudinal direction so as to be an inner surface of a concrete pipe to form an inner mold, and an adhesive is applied to the outer peripheral surface of the synthetic resin pipe. A method is disclosed in which an outer mold frame is erected on the outside of the inner mold frame at a predetermined interval in parallel with the inner mold frame, and then concrete is placed between the inner mold frame and the outer mold frame.

JP 2001-260124 A

  However, since the vibration pressure forming method imparts vibration to the mold as described above, it is necessary to attach a fixture or the like so that the synthetic resin pipe as the inner mold does not shift. Installation and removal work is required, which takes time. In the method disclosed in Patent Document 1, a special adhesive is applied to the outer peripheral surface of the synthetic resin pipe for adhesion to the concrete pipe, and such an adhesive application step is necessary. This also complicates the manufacturing process.

  Furthermore, in the method disclosed in Patent Document 1, it is assumed that only general-purpose concrete is placed. However, the general-purpose concrete disclosed in Patent Document 1 is poor in self-filling property, and this When the hydrodynamic molding method is performed using concrete with poor self-filling properties, the problems of the hydrodynamic molding method such as the above-mentioned corner chipping and voids such as bean plate occur, and the synthetic resin tube and the concrete are integrated. The strength required for concrete pipes may not be obtained.

  In addition, as a unique problem due to the steel pipe being provided on the outer peripheral surface, when the integrity of steel and concrete cannot be maintained, steel and concrete exhibit the same deformation behavior with respect to the load due to the effect of bean sheets and voids. As a result, there also arises a problem that the external pressure strength is reduced.

  The present invention has been made to solve the problems caused by the conventional centrifugal molding method and vibration pressure molding method as described above. The present invention is a concrete product with high productivity, good working environment, no generation of sludge, excellent product solidity, and a synthetic resin pipe is provided on the inner peripheral surface. An object of the present invention is to provide a method for producing a concrete product, which is a concrete product provided with steel, and is capable of producing a concrete product in which the integrity of the synthetic resin pipe and the concrete and the integrity of the steel and the concrete are enhanced. And

The present invention is a method for manufacturing a concrete product having a synthetic resin pipe on the inner peripheral surface and a steel material on the outer peripheral surface, and the synthetic resin pipe has grooves formed along the circumferential direction on the outer surface. An inner frame consisting of synthetic resin pipes that make up the inner surface side of the concrete product without removing it after placing concrete, and the outer surface side of the concrete product without removing it after placing the concrete. made of a steel material for constituting between the outer frame, the expansion amount is 150 × 10 ^-6 ~1000 × 10 ^-6 and Do Ri and inflate side in length change is three months after the concrete after curing of the concrete It said concrete remains expansion material is added and the slump flow is Da設the above high-flow concrete 65cm, allowed to stand the inner frame and outer frame as shown in the To provide a method of manufacturing a concrete product, which comprises shaping.

In the method for producing a concrete product according to the present invention, preferably, the synthetic resin pipe is a synthetic resin pipe in which a plurality of grooves formed along the circumferential direction on the inner surface thereof are formed in the axial direction. To do. Further, preferably, the high fluidity concrete has a slump flow 50 cm arrival time of 5 to 10 seconds . More preferably, the expansion material is a calcium sulfoaluminate-based expansion material, and the amount of the expansion material added is 20 to 50 kg per 1 m ^{3 of} concrete.

  The present invention also provides a concrete product manufactured by the method for manufacturing a concrete product as described above.

When a synthetic resin pipe with a plurality of grooves formed along the circumferential direction on the outer surface is used as the inner frame, the space between the grooves formed on the outer surface is filled with high-fluidity concrete. Compared with the case where a synthetic resin pipe in which no groove is formed is used, the integrity of the concrete and the synthetic resin pipe can be improved.
Moreover, since the high fluidity concrete with a slump flow of 65 cm or more is excellent in self-filling property, such a high fluidity concrete is placed between the inner frame made of synthetic resin pipe and the outer frame made of steel. Since the gap between the grooves formed on the outer surface of the synthetic resin pipe is easily filled with the high-fluidity concrete, the integrity of the concrete and the synthetic resin pipe can be further enhanced.
Further, by using the high fluidity concrete, it is possible to obtain a concrete product in which the space between the inner frame and the outer frame is densely filled. Moreover, since such a solid concrete product can be obtained without adopting the centrifugal molding method or the vibration pressure molding method, the centrifugal molding method is used between the synthetic resin tube provided on the inner peripheral surface and the concrete. Such a gap is unlikely to occur, and it is possible to manufacture a concrete product excellent in the integrity of concrete and a synthetic resin tube and concrete and steel without using an adhesive.
In addition, since no special equipment such as centrifugal molding or vibration pressure molding is required, the productivity is high and the working environment is good. Simple concrete products can be manufactured easily.

In addition, when high-fluidity concrete to which an expansion material is added is placed between an inner frame made of a synthetic resin pipe and an outer frame made of a steel material, the shrinkage of the concrete is suppressed or the concrete expands. Therefore, gaps are less likely to occur between concrete and synthetic resin pipes, or between concrete and steel materials, and the concrete and synthetic resin pipes, and the concrete and steel materials can be integrated without taking measures such as adhesive prevention. The sex can be further enhanced.
Furthermore, the concrete product according to the present invention is in a solid filling state and is low in manufacturing cost.

  As described above, the method for producing a concrete product according to the present invention uses a synthetic resin pipe in which a plurality of grooves formed along the circumferential direction on the outer surface are formed in the axial direction as the synthetic resin pipe. A high-fluidity concrete with a slump flow of 65 cm or more is placed between the inner frame made of the synthetic resin tube that constitutes the inner surface side of the concrete product without being removed later, and the outer frame made of steel, and the inner side By molding the concrete while leaving the frame and the outer frame stationary, a concrete product having a synthetic resin tube on the inner peripheral surface and a steel material on the outer peripheral surface is manufactured.

  Hereinafter, an embodiment of a synthetic resin pipe used in a method for producing a concrete product according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an example of an embodiment of a synthetic resin pipe used in a method for producing a concrete product according to the present invention, and is a longitudinal sectional view (a) of the synthetic resin pipe cut in the axial direction and a plane perpendicular to the axial direction. The cross-sectional view (b) cut | disconnected by is shown.

The synthetic resin pipe in which a plurality of grooves formed along the circumferential direction on the outer surface, which is the present embodiment, is formed in the axial direction. For example, as shown in FIG. The corrugated shape of the mold. That is, in the synthetic resin tube of the present embodiment, the corrugated recesses on the outer surface are a plurality of grooves 1a formed on the outer surface along the circumferential direction. On the other hand, the corrugated convex portions on the outer surface of the synthetic resin tube form a plurality of protrusions (hereinafter also referred to as ribs 1b) on the outer surface.
The interval between the projections (hereinafter also referred to as pitch 1c) is determined by the use, strength, and manufacturing convenience of the synthetic resin tube, but is usually about 10% of the inner diameter of the synthetic resin tube.
In addition, the shape of the protrusion may be an arbitrary shape such as a rectangular shape, a square shape, a trapezoidal shape, an arc shape, or a protruding shape, instead of the corrugated shape as in the present embodiment.

  As shown in FIG. 2B, the synthetic resin tube of the present embodiment is circular in the cross-sectional view. Further, instead of being circular as in the present embodiment, the synthetic resin tube may be, for example, oval or polygonal in a cross-sectional view.

The thickness of the synthetic resin pipe ((outer diameter−inner diameter) / 2) is appropriately selected in consideration of the use of the concrete product provided with the previous synthetic resin pipe, required strength, optimum manufacturing conditions, etc. The range is from about 3 mm to about 18% of the inner diameter of the synthetic resin tube. The thickness is about 15% of the inner diameter of the synthetic resin tube until the inner diameter of the synthetic resin tube is about 1200 mm. If the inner diameter of the synthetic resin tube exceeds 1200 mm, it is 10% or less of the inner diameter of the synthetic resin tube. It is.
Furthermore, the height difference of the protrusion, that is, the difference in height between the deepest portion of the groove 1a and the protruded portion of the rib 1b is preferably about 30 to 95% of the thickness.

  The inner diameter 1e of the synthetic resin pipe is an inner diameter corresponding to “A-6 standard: inner diameter 200 to 700 mm” or “A-2 standard: inner diameter 800 to 3000 mm” of the Japan Sewerage Association standard.

  The length of the synthetic resin pipe is the same as the length of a concrete product (for example, a concrete pipe) manufactured using the synthetic resin pipe.

  When the synthetic resin pipe having such a structure is used for manufacturing a concrete product, the concrete is filled between the ribs 1b, and the synthetic resin pipe is compared with a synthetic resin pipe in which the rib is not formed on the outer surface. Integration with concrete is further improved.

  In the synthetic resin tube, it is preferable that a plurality of grooves formed along the circumferential direction are formed on the inner surface as well as the outer surface in the axial direction. Moreover, the roughness coefficient of the inner surface of the synthetic resin tube is preferably 0.005 to 0.03. Adjusting the flow rate of sewage passing through the inside of the synthetic resin pipe when the concrete pipe using the synthetic resin pipe is used as, for example, a sewage pipe by adjusting the unevenness and roughness coefficient of the inner surface Can do.

The high-fluidity concrete having a slump flow of 65 cm or more used in the present invention is obtained by measuring the slump flow of fresh concrete by the method specified in “Method of testing slump flow of concrete” in JIS A 1150. It is a concrete whose average value of the measurement results is 65 cm or more.
Therefore, for example, when the measurement result obtained by the test method described in the above JIS is a slump flow of 70.0 × 69.0 (cm × cm), the average value is 69.5 (cm ) Is the slump flow in the present invention.

Further, in the high fluidity concrete having a slump flow of 65 cm or more used in the present invention, it is preferable that the time for the slump flow to reach 50 cm (also referred to as the slump flow 50 cm arrival time in the present invention) is 5 to 10 seconds. .
Use of such a high-fluidity concrete has an effect that the mold can be filled uniformly without causing material separation.

The composition of such high fluidity concrete is not particularly limited, for example, adjustment of water / binder ratio, addition of admixtures such as silica fume, fly ash, blast furnace slag fine powder, limestone fine powder, or It can be obtained by adjusting the fluidity by adding an admixture such as a water reducing agent, a high performance water reducing agent, and a high performance AE water reducing agent.
The water / binder ratio here refers to the weight of water relative to the total weight of cement as a binder and cement admixture (silica fume, fly ash, blast furnace slag fine powder, etc.) having pozzolanic activity or hydraulic properties. Ratio (%).

  In particular, in the present invention, it is preferable to prepare a high-fluidity concrete having a predetermined slump flow by blending silica fume.

  When silica fume is used, specifically, it is preferably blended so as to have a replacement amount of 5 to 25% by weight with respect to the cement, and more preferably blended so as to have a replacement amount of 10 to 20% by weight. preferable.

From the viewpoint of increasing the strength of the concrete product to be produced, it is preferable that the silica fume, water reducing agent, etc. are blended to make the water / binder ratio 40% or less.
That is, by preparing high-fluidity concrete by blending silica fume, water reducing agent, etc., the fluidity in the fresh state can be enhanced while keeping the water / binder ratio low, and therefore the strength of the concrete product after curing is increased. There is an effect that it can be increased.

  Although it does not specifically limit as said silica fume, The thing which has silicon dioxide as a main component and contains a zirconium oxide (henceforth a specific silica fume) can be used suitably. The specific silica fume is obtained mainly as a silica fume by-produced in the production process of zirconia, and has a larger average particle size and a lower pH than a conventional general silica fume. Therefore, such a specific silica fume has the property that most of the particles are present in the state of primary particles and hardly agglomerate, and also has the effect that the setting delay action of concrete is moderately exerted and the fluidity is hardly lowered. have.

  In addition, when such a specific silica fume is used in combination with an expansion material, it becomes a high fluidity concrete that does not cause material separation and has good self-filling properties. Then, the concrete is prepared with a water / binder ratio of 30% or less, placed in a mold, and the concrete is molded while the mold is allowed to stand, so that conventional molding such as centrifugal molding and vibration molding is performed. It becomes possible to manufacture a concrete product having strength and aesthetics equivalent to or higher than the manufacturing method.

  The specific silica fume is not particularly limited with respect to its production method, raw material, and the like, but those mainly produced as a by-product in the production process of zirconia can be preferably used. Further, the silica fume does not have to satisfy the quality defined in JIS A 6207 “Silica fume for concrete”.

  The amount of silicon dioxide that is the main component of the specific silica fume is preferably 85% by weight or more, and more preferably 90% by weight or more. Further, the content of zirconium oxide as one component of the specific silica fume is preferably 1 to 10% by weight, more preferably 3 to 5% by weight.

The specific silica fume preferably has a specific surface area of 10 m ² / g or less, more preferably 9 m ² / g or less. Conventionally, silica fume generally used as an admixture for cement has a specific surface area of 15 m ² / g or more, whereas the silica fume has a relatively small specific surface area as described above. .

  The specific silica fume preferably has an average particle size of 0.5 to 1.5 μm, more preferably 0.8 to 1.2 μm. If the average particle size of the specific silica fume is in the above range, the aggregation of the specific silica fume is suppressed, the dispersibility in the concrete is good, and the predetermined fluidity is exhibited even when used in combination with an expansion material. As with conventional silica fume, it is possible to produce dense concrete with high strength by the microfiller effect and the pozzolanic reaction.

  The average particle size of silica fume is measured based on the Japan Cement Association “Standard Test Method (CAJS K-03-1982 / Friction Test Method Using Air Jet Sieve Device)”.

In addition, when silica fume is blended in the present invention, the silica fume preferably has a pH of 2.5 to 6.5, more preferably 4.0 to 5.0. If the pH of the silica fume is in the above range, the setting delay action of the concrete is adequately exerted, so the flow loss is reduced, the workability at the time of construction is improved, and the denser and higher strength concrete. There is an effect that can be manufactured.
The pH of silica fume is measured based on JIS Z 8802-1986 “pH measurement method”.

  Furthermore, in the present invention, it is preferable to add an expansion material to the high fluidity concrete. The type of the expansion material is not particularly limited, and a conventionally known expansion material can be used. Among them, an expansion material having a quality defined in JIS A 6202 “Expansion material for concrete” can be preferably used. it can.

  Specifically, as the expanding material, calcium sulfoaluminate-based and quicklime-based expanding materials can be used alone or in combination.

When adding the expansion material to the high fluidity concrete, it is preferable to add the expansion material so that the expansion amount of the concrete is 150 × 10 ^{−6 to} 1000 × 10 ⁻⁶ , and the expansion amount of the concrete is 500 it is preferable to add an expansion member so as × a 10 ^-6 ~800 × 10 ^-6. If the amount of expansion of the concrete is in the above range, the concrete expands appropriately due to the action of the expansion material, and the synthetic resin tube and the concrete are more well integrated. In particular, it is particularly effective that the length change of the concrete after hardening is not contracted but on the expanded side even after three months.
In addition, the amount of expansion of concrete is converted to a ratio of “length change rate L _r (%)” obtained based on method B of JIS A 6202 Annex 2 “Testing Method for Restrained Expansion and Shrinkage of Expanded Concrete”. That is, the value obtained by dividing the “length change rate L _r (%)” by 100.

When the expansion material is a calcium sulfoaluminate-based expansion material, the addition amount of the expansion material is preferably 20 to 50 kg, more preferably 30 to 40 kg per 1 m ^{3 of} concrete. By setting the upper limit of the amount to be added as described above, it is possible to reduce the risk of the unreacted expansion material expanding slowly and destroying concrete.

  Moreover, when using a silica fume and an expansion material together, it is preferable that the mixing ratio (weight ratio) of a silica fume and an expansion material shall be silica fume: expansion material = 60: 40-70: 30, and a silica fume: expansion material = 60: It is more preferable to set it as 40-65: 35.

  In addition, the cement used in the present invention is not particularly limited. Examples of the cement include normal, early strength, ultra-early strength, white, sulfate-resistant salt, moderate heat, low heat, and other Portland cements, the Portland cement. Examples thereof include special cements such as mixed cement obtained by mixing blast furnace slag, fly ash, etc., jet cement, and alumina cement.

The amount of water in preparing the concrete is preferably such that the water / binder ratio is 40% or less, more preferably 15 to 30%, and particularly preferably 10 to 20%.
By setting the water / binder ratio in such a range, it was possible to perform demolding in a short time after filling while maintaining excellent self-filling property when filling into the frame, and manufactured. Concrete products have high compressive strength and external pressure strength.
In particular, by producing a high-strength concrete pipe with a water / binder ratio of 10 to 20%, the produced concrete pipe can be laid in the ground using a propulsion pipe method. .

  When preparing concrete, various materials as described above are kneaded using various conventionally known concrete mixers.

  A concrete product can be obtained by placing the concrete prepared as described above between an inner frame and an outer frame, and molding and curing the concrete while the frame is left standing. . In the present invention, a synthetic resin pipe in which a plurality of grooves formed in the outer surface along the circumferential direction is formed in the axial direction is used as the inner frame, and various steel materials such as a steel pipe are used as the outer frame.

  That is, when a concrete product having a desired shape such as a concrete pipe is manufactured according to the present invention, an inner frame made of a synthetic resin pipe and an outer frame made of a steel pipe are installed in advance, and the inner frame and the outer A concrete product having a predetermined shape can be obtained by placing the concrete prepared as described above between the frames, molding the concrete while leaving the formwork still, and curing the concrete. .

  Here, as the material of the synthetic resin tube, for example, a thermoplastic resin made of polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl chloride, fluororesin, ABS resin, AS resin or the like is used. Can do. The synthetic resin is selected according to the application of the concrete product to be manufactured.

  On the other hand, as said steel material, what consists of stainless steel, iron, etc. can be used, for example.

  The said outer frame can use the thing of arbitrary structures according to the target concrete product. In particular, the high-fluidity concrete used in the present invention has a high self-filling property as described above, and does not require centrifugal molding or strong vibration during filling. It is not necessary to use a highly rigid material that can withstand Also, the shape of the frame can be any shape, and the type of concrete product is not limited to the concrete pipe, and can be products of various shapes.

  The high-fluidity concrete used in the present invention has a slump flow of 65 cm or more as described above and has a high self-filling property. Therefore, when filling the concrete into the frame, centrifugal molding or strong There is no need to apply vibration. However, vibrations may be applied within a range in which material separation does not occur from the viewpoint of surely preventing corner chipping, bean plate, and the like from occurring on the concrete surface.

  Moreover, it is also possible to shape | mold as a concrete product containing reinforcing bars, such as a reinforced concrete pipe, by arranging a reinforcing bar in the frame beforehand.

  Specifically, the concrete self-filled in the frame has a strength capable of handling the product in at least 24 hours.

As described above, according to the method for producing a concrete product according to the present invention, it is not necessary to use a high-rigid formwork that has been used in the conventional production method, and thus the steel material that reinforces the formwork is omitted. This can greatly reduce the production cost of the formwork.
Further, according to the method for producing a concrete product according to the present invention, a large noise is not generated at the time of molding, so that the working environment is improved and no sludge is generated, so that the processing cost is not required.
Further, since a large-sized device such as a centrifugal molding device or a vibration molding device is not required, there is an advantage that the cost required for capital investment is lower than that in the past.
In addition, there is an advantage that a concrete product excellent in unity between the steel material provided on the outer side, the synthetic resin pipe provided on the inner side, and the concrete filled therebetween is provided.

  The materials shown in Table 1 below were kneaded with the composition shown in Table 2 below using a biaxial forced kneading mixer with a capacity of 55 liters to prepare Preparation Example 1 and Preparation Example 2 concrete.

(Measurement of fresh properties)
Regarding the concretes of Preparation Example 1 and Preparation Example 2, the slump flow defined in JIS A 1150 “Slump Flow Test Method for Concrete” was measured as a fresh property when the concrete was prepared. The measurement results are shown in Table 3 below.

(Compressive strength test)
Based on the test method defined in JIS A 1108 “Testing method for compressive strength of concrete”, the compressive strength of the concrete of Preparation Examples 1 to 5 on the 14th day of the φ10 × 20 cm specimen was measured. The measurement results are shown in Table 3 below.

(Measurement of concrete expansion)
The expansion amount of the concrete was measured based on the method B of JIS A 6202 Annex 2 “Testing Method for Restrained Expansion and Shrinkage of Expanded Concrete”. The results are shown in Table 3 below.

  Next, concrete pipes were prepared using the concrete of Preparation Example 1 and Preparation Example 2, and the integrity of the concrete, the synthetic resin pipe, and the steel pipe was evaluated.

( Comparative Example 3 )
As a synthetic resin pipe having a plurality of grooves formed in the outer surface along the circumferential direction in the axial direction, a polyethylene synthetic resin pipe “corrugated pipe CW-100 type” having an outer diameter of 117 mm, an inner diameter of 100 mm, and an effective length of 300 mm (product) Name, made by Dainippon Plastic Co., Ltd.) to produce a concrete pipe. The synthetic resin pipe is set on the inside, and a steel pipe (outer diameter 200 mm, pipe thickness 2.3 mm, effective length 300 mm) is set on the outside. Between the inner frame made of the synthetic resin pipe and the outer mold frame, The concrete obtained in Preparation Example 1 was placed. When placing, both the synthetic resin pipe and the steel pipe were placed so that the effective length direction was vertical, and concrete was poured from above at a speed of 100 mm / min. Then, after 24 hours had passed from placing, sealing was performed with a vinyl sheet, and the concrete tube of Comparative Example 3 was produced by curing in a thermostatic chamber at 20 ° C. for 13 days after sealing.

(Example 1 )
A concrete pipe was produced in the same manner as in Comparative Example 3 except that the concrete obtained in Preparation Example 2 was used.

(Comparative Example 1)
A concrete pipe was produced in the same manner as in Comparative Example 3 except that a synthetic resin pipe having a smooth outer surface, an outer diameter of 114 mm, a pipe thickness of 3.1 mm, and an effective length of 300 mm was used.

(Comparative Example 2)
Concrete in the same manner as in Comparative Example 3 except that the outer surface is smooth, a synthetic resin pipe having an outer diameter of 114 mm, a pipe thickness of 3.1 mm, and an effective length of 300 mm is used, and the concrete obtained in Preparation Example 2 is used. A tube was made.

(Integrity evaluation between concrete, synthetic resin pipe and steel pipe)
When the load was applied to the concrete pipe of Example 1 and Comparative Examples 1 to 3 obtained in the pressure tester so that a load was applied in the radial direction, and the load was applied at a loading speed of 0.5 mm / min, The load when a crack was confirmed was measured. The results are shown in Table 4 below.

As shown in Table 4, the concrete pipes of Comparative Example 3 and Example 1 have higher crack loads indicating the strength in the radial direction than the concrete pipes of Comparative Example 1 and Comparative Example 2, respectively. Is recognized. This result is the same whether the concrete is not blended with an expansion material or is concrete mixed with an expansion material. The crack load of the concrete pipe of the example was increased because the concrete was filled between the projections of the irregularities of the synthetic resin pipe having the irregularities formed on the outer surface. This is thought to be due to the increased unity. Further, the concrete pipe of Example 1 using the concrete of Preparation Example 2 containing the expansion material is more cracked than the concrete pipe of Comparative Example 3 using the concrete of Preparation Example 1 containing no expansion material. It can be seen that the load is 24% higher. On the other hand, in comparison with the concrete pipe of Comparative Example 1 using the concrete of Preparation Example 1 containing no expansion material, the crack load of the concrete pipe of Comparative Example 2 using the concrete of Preparation Example 2 containing the expansion material is higher. A 16% increase. From this result, it is considered that the increase in cracking load is due to the fact that the concrete expands due to the addition of the expansion material, and the integrity of the concrete and the synthetic resin pipe is increased. Here, since the unevenness is further formed on the outer surface of the synthetic resin tube, the rate of increase in cracking load is changed from 16% to 24%. The use and the use of concrete mixed with an expansion material have an unpredictable effect on the integrity of the concrete and the synthetic resin pipe.

  The method for producing a concrete product according to the present invention is not limited to products such as rebars or unreinforced concrete pipes conventionally produced by centrifugal molding, but also various cements 2 such as box culverts, retaining walls, water tanks, side grooves, and RC segments. It can also be applied to the production of next products.

(A) Longitudinal sectional view showing a synthetic resin tube of one embodiment (cross sectional view showing a section when cut in the axial direction), (b) Cross sectional view (cross section taken along a plane perpendicular to the axial direction) FIG. The cross-sectional perspective view which shows the concrete product of one Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Synthetic resin pipe 1a ... Groove 1b ... Rib 1c ... Pitch 1d ... Outer diameter 1e of synthetic resin pipe ... Inner diameter 2 of synthetic resin pipe ... Concrete product 3 ...・ Concrete 4 steel pipe

Claims (5)

A method of manufacturing a concrete product having a synthetic resin pipe on an inner peripheral surface and steel on an outer peripheral surface, wherein the synthetic resin pipe has a plurality of grooves formed along the circumferential direction on the outer surface in the axial direction. Using the formed synthetic resin pipe, the inner frame made of the synthetic resin pipe that constitutes the inner surface side of the concrete product without being removed after the concrete is cast, and the outer surface side of the concrete product are constituted without being removed after the concrete is cast. between the outer frame made of steel, so that the length variation of the concrete after curing amount of expansion of the concrete and Ri Do and 150 × 10 ^-6 ~1000 × 10 ^-6 is in the expansion side after three months A high-fluidity concrete with a slump flow of 65 cm or more is placed in it, and the concrete is molded with the inner and outer frames stationary. Method for producing a concrete product according to claim Rukoto.   The method for producing a concrete product according to claim 1, wherein the high fluidity concrete has a slump flow 50 cm arrival time of 5 to 10 seconds. The method for producing a concrete product according to claim 1 or 2, wherein the expansion material is a calcium sulfoaluminate-based expansion material, and the addition amount of the expansion material is 20 to 50 kg per 1 m ³ of concrete.   The method for producing a concrete product according to any one of claims 1 to 3, wherein the synthetic resin pipe is a synthetic resin pipe in which a plurality of grooves formed along the circumferential direction on the inner surface are formed in the axial direction.   A concrete product manufactured by the method for manufacturing a concrete product according to claim 1.

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